A rare occurrence of the neurotoxin that causes botulism has killed 23 horses this month – including five in one night – at a farm in Gorham.

The toxin is not contagious and may have been in the animals’ feed, said Don Hoenig, the state veterinarian. “It’s kind of a tragic story for the people who own the horses.”

The concern now is proper disposal of the carcasses, which are buried at the farm, he said. A compliance officer and a soil scientist visited the farm Friday to explore options.

Hoenig said the farm is on Nonesuch Road and belongs to the Kozloff family. A website for Whistlin’ Willows Farm at 17 Nonesuch Road lists William and Anne Kozloff. They could not be reached at the telephone number listed for the farm and did not respond to an email by press time.

State officials learned of the horses’ deaths last week, after someone lodged a complaint, though it appears there was no failure to care for the animals properly, Hoenig said.

Botulism is caused by a powerful and fast-acting toxin given off by the bacteria Clostridium botulinum. It can kill a horse within hours after it is ingested, Hoenig said. When people contract it, it is usually from improperly canned food.

Botulism is often fatal, but there is no test to confirm that it killed the horses. Searching in tissue for the minute amount of toxin it takes to be fatal is difficult and often inconclusive. Instead, veterinarians must diagnose the condition from the symptoms, he said.

A local veterinarian went to the farm on April 12 and euthanized five animals, Hoenig said. A colleague had euthanized two horses two days earlier.

“She told me the horses were exhibiting signs of classic botulism, which is essentially severe neurologic disease,” Hoenig said. “Generally, horses go down and lie on their side. The disease results in some paralysis. Usually, it’s hard to bring them back from it.”

Some of the horses that were showing symptoms have recovered, and the rest of the herd – 40 to 45 horses – appears to be doing well, Hoenig was told. The deaths started on April 7.

State inspectors suspect that the bacteria grew in bales of what is called baleage or haylage. Unlike hay, which is dried before being baled, baleage is baled in white plastic while it still has high moisture content. It ferments as a mechanism for preservation.

Hoenig said such silage generally is not recommended for horses that have not been vaccinated for the family of bacteria that includes Clostridium botulinum. The person who provided the feed to the horses in Gorham is working with state officials to determine whether it could be responsible, he said.

“There may have been other feeds and we’re kind of the middle of this investigation,” Hoenig said. “We don’t know for sure whether there could have been another source of feed there.”

No other unusual equine deaths have been reported to the state recently, he said.

Hoenig said he has not seen botulism poisoning in his professional career, though he saw it four times in veterinary school. He spoke with other veterinarians who had seen it once or twice.

The farm apparently sells and takes in various breeds of horses, and boards some animals, though Hoenig said he believes that most of the animals are owned by the Kozloffs.

State officials’ first concern was that the deaths might represent a contagious disease, he said. They also worried that the deaths might be related to poor care. Neither appears to be the case.

State officials are concerned about the disposal of the animals’ carcasses. The 23 dead horses are buried at the farm, about 8 feet deep, Hoenig said. That puts them in proximity to the water table.

Hoenig’s staff has researched botulism and found little likelihood that the toxin can spread through water. If some did come in contact with water, it would be diluted to beyond what is harmful.

“We’re more concerned just about the deterioration of the carcasses and potential runoff into wetlands or in streams,” he said.

A state compliance inspector and a soil scientist are working with the farm owners on a plan to prevent water from leaching through the carcasses, and the owners have been cooperative, Hoenig said. The carcasses may be dug up and composted, he said.

Staff Writer David Hench can be contacted at 791-6327 or at:

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